The odorless, colorless gas is often used as a fumigant.
The country's Deputy Commerce Minister Yanyong Phuangrach has demanded to know the identity of the laboratories the consumer group commissioned to test the packaged rice, the Bangkok Post reported Wednesday.
Deputy Commerce Minister Nattawut Saikuar said he would ask the authorities to conduct testing again for accuracy. and called on the consumer group to send the samples to the Department of Agriculture and the Department of Rice for testing.
The Foundation for Consumers released the results of chemical and fungicide contamination tests on 46 packed rice samples Tuesday.
Foundation Secretary-General Saree Aongsomwang said the rice products were tested at university and privately run laboratories but refused to disclose their names.
Saikuar called on the consumer group to send the samples to the Department of Agriculture and the Department of Rice for testing.
"They must reveal where the packed rice is tested and how much of the residue is found," Saikuar said.
Somkiat Makkcayathorn, president of the Thai Rice Packers Association, insisted rice remains safe for consumption and that any residue of the methyl bromide would dissolve when the rice is cooked.
However, he said, rice samples with high levels of fumigant would be recalled and tested.
"Consumers can be assured that the packed rice being sold in the market is safe," he said.